Travel Health Thursday June 30, 2016

How Old Is Malaria?

The World Health Organisation states there were 200 million cases of malaria in 2015 with 438,000 deaths. It's a current global concern, but in terms of history malaria is one of the oldest killers around. It's so old it may have even shaped the history of evolution.

How Old?

There are two interesting studies about the evolution of malaria. The first traces its origins back to the age of dinosaurs.

Dinosaur Malaria

An article published in the American Entomologist investigated the fossil of an early to mid Cretaceous (that's 145-66 million years ago) biting female midge captured in Myanmar amber.

This midge appears to be infected with a malaria parasite called Paleohaemoproteus burmacis. This challenges the current view that modern malaria evolved from the Anopheles mosquitoes between 15,000 to 8 million years ago.

Experts suggest that the fossil shows an older version of today's Anopheles borne disease, and some speculate that an early form of malaria may have affected the dinosaur species given that they were declining before whatever catastrophic event ended their reign on earth.

Early Human Malaria

Another study from the Biotechnology and Biological Sciences Research Council suggests that modern malaria travelled out of Africa with our ancestors 60- 80,000 years ago making it 10,000 years older than previously thought.

Researchers investigated the largest collection of malaria parasites collected so far and sequenced them by DNA to track progress across the tropics. They found decreasing genetic diversity as humans moved away from sub-Saharan Africa which reflects the pattern of human activity back then. Researchers believe this is evidence of co-evolution through a shared geographical spread.

The research on the history of malaria is important because it helps to uncover its genetic diversity and supports development of drugs that overcome the mosquito parasites' immune systems.

What is Malaria?

Malaria is a very serious tropical blood illness. It's caused by the parasite 'plasmodium'. Anopheles mosquitoes spread this parasite when they bite. It's a single-celled organism that spreads quickly and easily in the bloodstream.

Once in the bloodstream the parasite rests in the liver and begins to multiply. It then spreads throughout the bloodstream. Red blood cells are infected and burst by the parasite which then infects more red blood cells.

Plasmodium parasites number in their hundreds but the most common ones that bite humans are P. Falciparum and P. Vivax. The most deadly infection is P.Falciparum. It's the most common and causes the most deaths. P. Vivax can lie dormant for three years causing relapses. P. malariae, P. Ovale, and P. Knowlesi can also infect humans but are less common types.

Where Is Malaria Found?

Malaria is spread by mosquitoes which need hot humid conditions to survive. The UK is not yet hot enough to support fatal forms of malaria. It's generally found in:

  • Sub-Saharan Africa
  • North Africa
  • South and Central Asia
  • Central and South America
  • The Caribbean
  • The Middle East
  • Papua New Guinea, the Solomon Islands, and Vanuatu

If you plan to visit any of these locations you must be prepared against malaria. Malaria can also be spread through birth from mother to child, by sharing needles and blood transfusions although these forms of transmission are rare.

Is Malaria the Same As Zika?

The similarity between the Zika virus and malaria is that they are both spread by mosquito bites. Zika is not malaria.

Malaria is spread by the Anopheles mosquito which usually bites in the evening and during the night. Zika is spread by the Aedes mosquito that generally bites in the daytime. Zika may also be spread by sexual contact.

Zika and malaria both cause serious birth defects but Zika does not generally have such severe symptoms in the individual. Most Zika infections cause mild, flu like symptoms plus:

  • Fever
  • A rash
  • Headaches
  • Joint pain and swelling
  • Muscle pain
  • Conjunctivitis
  • Lower back pain
  • Pain behind the eyes

What Are The Symptoms Of Malaria?

The plasmodium parasite incubation time lies between 7-18 days depending on which type has been contracted. In some cases it can lie dormant in the liver and take years to produce any symptoms.

Symptoms can present in cycles as red blood cells burst every 48-72 hours.

The initial symptoms of malaria include:

  • Sweating
  • Chills
  • Vomiting
  • Headaches
  • Mild flu like symptoms
  • Muscle pain
  • Diarrhoea

Later on patients can become anaemic and develop organ failure. If untreated malaria can cause coma and eventually death.


How To Prevent Malaria

Taking a course of anti-malarial tablets is essential if you plan to travel to malaria infected countries. There is no vaccine for malaria despite years of research into the possibilities.

Antimalarial drugs such as doxycycline, malarone, paludrine and avloclor need to be taken in advance of travel, some require three weeks of advance treatment, and after you return to cover the incubation period.

They work by preventing plasmodium's ability to breed. This allows your immune system to kill the original infection. No course of tablets is 100% guaranteed but chances are increased if you take them correctly.

Other anti-mosquito precautions include:

  • Applying anti-mosquito creams and repellents to prevent bites. The chemical DEET provides effective protection against bites.
  • Spraying or using heated insecticides in household rooms.
  • Using an insecticide impregnated mosquito net at night.
  • Keeping limbs covered particularly during the evening such as long trousers and tops. Elasticised wrists and ankles are helpful.
  • Babies, young children, pregnant women and the immuno-compromised are especially at risk of malaria. Think carefully about travelling to infected areas.

Travellers must be prepared or they are likely to face a very serious illness. Those travelling to affected areas should always take a course of anti-malarial tablets even if they are staying in a city environment with friends and family. Mosquitoes are wide-spread. They need water to breed but this can be in a pond, rain puddles or rivers which are found country-wide.

Although malaria is a very old disease, it's proved impossible to eradicate perhaps due to its co-evolution. Needless to say, malaria is still dangerous today and should never be underestimated.

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